There are twelve weapon slots in the game and one special weapon slot for players to fill their wheel with. These are unlocked throughout the game and found in some of the harder-to-reach places later on.
Claude’s pager will notify the player when a weapon unlocks that a weapon is now available in stores. While players can purchase most weapons from Ammu-Nation after completing missions, some weapons are sold elsewhere. Phil Cassidy’s Army Surplus will allow the player to buy Shotguns for $1,500, M16s for $5000, and Rocket Launchers for $25,000.
After completing the Arms Shortage mission, Phil’s shop unlocks and is the only place the player can buy the Rocket Launcher.
For more guides on Grand Theft Auto 3, check out How to make money in Grand Theft Auto 3 – The Definitive Edition on Pro Game Guides.